(A) Field of the Invention
The present invention is related to a rotation apparatus of a dish antenna. More specifically, the rotation apparatus of the dish antenna is capable of adjusting the elevation angle and the rotation angle.
(B) Description of Related Art
The satellite television system employs a dish antenna to collect satellite signals, and the signals are then reflected to low noise block down converters (LNB) equipped at the focus of the dish antenna for amplifying the signals and reducing its frequency down to around 1 GHz, i.e., the signals of radio frequency are transformed to be of intermediate frequency. The adjusted signals are transmitted to an indoor TV channel selector by a cable to select the signals of a desired channel, and the selected signals are then amplified and modulated to recover into video and audio signals for TV watching.
Dish antenna is a high directional receiving device which has to precisely direct to satellites on the orbit of 36,000 kilometers altitude. For example, if a dish antenna of a 180 cm diameter shifts 2 cm in transverse, or 3 cm in vertical, the signals will become weak or even disappeared. Therefore, the precision of the direction of the dish antenna is very important.
If a dish antenna has to direct to a plurality of synchronous satellites, the direction of the dish antenna has to be adjustable, which is usually done by adjusting the elevation angle and the rotation angle.
In accordance with the patent U.S. Pat. No. 6,445,361 B2, Liu discloses a rotation apparatus of a dish antenna including a dish bracket and an elevation bracket. The elevation bracket includes a central axle hole and three holes which surround the central axle hole. The central axle hole and the three holes respectively align with a concentric axle center and three circular grooves of the dish bracket to secure the dish bracket and the elevation bracket. After the dish antenna is rotated to a selected position, the three holes are secured to the circular grooves by three screws.
Originally, the elevation bracket is constituted by two individual components; one object of this patent is to integrate the individual components as a whole to enhance the rigidity. Generally, a satellite receiving system has to withstand 60 m/s of wind pressure. However, because the wind direction changes with respect to different seasons and weathers, a dish antenna has to withstand side wind in addition to the wind in a normal direction. Liu only utilizes three screws to secure the dish bracket and the elevation bracket, which may be insufficient to resist a large shear force.
The object of the present invention is to provide a high strength rotation apparatus of a dish antenna for enhancing the stability and obtaining better signal-receiving and signal-transmitting performance.
The rotation apparatus of the dish antenna of the present invention for adjusting a dish antenna to direct to a satellite comprises an elevation bracket and a dish bracket. The elevation bracket comprises two wings, a base and a cover, the two wing being approximately parallel, and each wing having a groove for adjusting the elevation angle of the dish antenna, the base connecting the bottoms of the two wings and being approximately parallel to them, and also being provided with at least a first fastener, and the cover being in the form of an arc and approximately perpendicularly connected to the base, and also having at least a second fastener. The dish bracket comprises a top plate and an arc plate, the top plate comprising at least one concentric groove for allowing the first fastener to slide therein, and the arc plate being approximately perpendicularly connected to top plate and having at least one arc groove for allowing the second fastener to slide therein. The dish antenna is adjusted to direct to the satellite by respectively sliding the first fastener and the second fastener in the concentric groove and the arc groove, and then the elevation bracket and the dish bracket are assembled by the first fastener and the second fastener.